The present invention pertains generally to catheters and methods for using such catheters. More particularly, the present invention pertains to rapid-exchange catheters. The present invention pertains particularly, though not exclusively, to single lumen rapid-exchange catheters.
During the performance of an interventional procedure, such as a percutaneous transluminal coronary angioplasty procedure, it is often necessary to exchange one catheter for another. For instance, after one catheter has been used to make an initial diagnosis, it may be necessary to remove the diagnostic catheter and replace it with a surgical catheter. Also, the sequential use of different surgical catheters may be required. During intervention, for example in an angioplasty procedure, lesions of the same vessel often require treatment with different size balloons. This requires that angioplasty balloon catheters having different size balloons be exchanged. Further, after a procedure has been completed, it may be desirable to reintroduce the diagnostic catheter to assess the progress that has been made. Still further, at the end of the treatment, it also may be desirable to introduce a drug delivery catheter to perfuse the lesion with agents that will inhibit or prevent a restenosis. Suffice it to say, during an interventional procedure in the vasculature, there are several occasions when it may be necessary or desirable to exchange catheters.
There are essentially two types of catheters that cooperate with guidewires for use in placement of the catheter in the vasculature of a patient. The first type of catheter is an xe2x80x9cover-the-wirexe2x80x9d catheter in which a guidewire lumen extends the full length of the catheter shaft. This type of catheter requires that the guidewire be sufficiently long for its proximal end to remain in place until the distal end of the catheter has been withdrawn from the patient. The second type of catheter is the so-called xe2x80x9crapid-exchangexe2x80x9d catheter in which the guidewire lumen does not extend the full length of the catheter shaft. Instead, the guidewire exits the catheter shaft at the distal end of the catheter, and at some point between the distal end and the proximal end of the catheter which is preferably closer to the distal end. Thus, when positioned in the vasculature, most of the guidewire extends externally in a proximal direction alongside the catheter shaft. This limits the interaction between the guidewire, and reduces the necessary extracorporeal length of the guidewire in comparison to the guidewire length required by the over-the wire catheters.
Rapid-exchange catheters typically have multiple separate lumens with one lumen dedicated as a guidewire lumen which can be used for the exchange of catheters. One example of such a rapid-exchange, multi-lumen catheter is disclosed in U.S. Pat. No. 5,346,505 which issued to Leopold for an invention entitled xe2x80x9cEasily Exchangeable Catheter System.xe2x80x9d Such a catheter has a guidewire lumen and an inflation lumen formed in the catheter body.
In any case, the present invention recognizes that rapid-exchange catheters having several lumens will typically have large cross-sectional areas. This is most likely undesirable because, in order to minimize trauma to a patient, it is desirable to make the smallest possible puncture in a patient""s body. Consequently, a catheter should have the smallest possible cross-sectional area.
In light of the above, and in a departure from the known art, it is the object of the present invention to provide a multi-purpose, single lumen rapid-exchange catheter that uses the same lumen for receiving a guidewire and for establishing fluid communication through the catheter. Another object of the present invention is to provide a rapid-exchange catheter having sealing ports that provide for a smooth and easy insertion and withdrawal of a guidewire therefrom without compromising the fluid communication function of the catheter. Yet another object of the present invention is to provide a rapid-exchange catheter which is relatively simple to manufacture, easy to use, and comparatively cost effective.
The present invention is directed to a single lumen rapid-exchange catheter. For the present invention, the rapid-exchange catheter includes a catheter tube having a single lumen which is suitable for dual purposes. First, the lumen is used to establish a fluid communication channel through the catheter. Second, the lumen is dimensioned for also receiving a guidewire. To do this, the catheter tube of the present invention includes a distal sealing port and a proximal sealing port which are formed into the catheter tube. Structurally, each of the sealing ports is tubular shaped and has a length and a diameter. Specifically, the length of each sealing port needs to be long enough to establish a substantially fluid-tight seal with the guidewire. The diameter of each sealing port, however, needs to be slightly greater than the diameter of the guidewire in order to allow the guidewire to pass through the sealing port. More specifically, when the guidewire is in a sealing port, there will be a distance between the diameter of the sealing port and the diameter of the guidewire that varies within a range between zero and approximately two thousandths of an inch (0 to 0.002 inches). Despite the fact this distance exists, it is still necessary that the port establish a substantially fluid-tight seal with the guidewire. The material that is used for the sealing port is important in this aspect.
As intended for the present invention, each sealing port preferably incorporates a hydrophilic polymer. Specifically, each sealing port preferably has an inner lining that extends along the length of the sealing port and that is made of a hydrophilic polymer. Consequently, upon exposure to a fluid, the hydrophilic material in the sealing ports become lubricious, and allow for the guidewire to slide through the sealing ports. Moreover, when fluid is present, each sealing port swells up against the guidewire to establish a substantially fluid-tight seal with the guidewire.
As envisioned by the present invention, in a catheter exchange, one catheter will be withdrawn from the vasculature, while the guidewire remains in situ. Thus, the subsequent engagement of a sequential catheter will first require insertion of the proximal end of the guidewire through the distal sealing port of the catheter and then the passing of the guidewire out of the proximal sealing port. To do this, there are a couple of features envisioned for the present invention. First, a diverter having a lip is disposed inside the lumen at the proximal sealing port of the catheter tube. The lip of the diverter extends radially into the lumen of the catheter tube to redirect the guidewire from inside the catheter tube through the proximal sealing port. Specifically, the diverter extends into the lumen of the catheter tube approximately one-half the diameter of the catheter tube. Secondly, the rapid-exchange catheter of the present invention can be formed with a shoulder which demarcates a proximal portion of the rapid-exchange catheter from a distal portion of the rapid-exchange catheter. More specifically, the shoulder causes a longitudinal axis for the proximal portion of the rapid-exchange catheter to be off-set from, and substantially parallel to, the longitudinal axis of the distal portion of the rapid-exchange catheter. The proximal sealing port is then located on the catheter tube at the shoulder in alignment with the longitudinal axis of the distal portion of the catheter tube. With this configuration for the catheter tube, a guidewire can be received through the proximal sealing port and the distal portion of the catheter tube without there being any significant bending of the guidewire.
In the operation of the present invention, a guidewire is first advanced into the vasculature of a patient. The proximal end of the guidewire is then inserted through the distal sealing port of the present invention extending through the lumen of the catheter tube, and through the balloon. The guidewire exits the catheter tube through the proximal sealing port of the present invention. The rapid-exchange catheter of the present invention is then advanced over the guidewire and into the vasculature of the patient.
When the rapid-exchange catheter has reached its desired position in the patient""s body, the balloon can be inflated to a desired pressure, such as eighteen atmospheres of pressure. Meanwhile, the guidewire remains in the catheter tube during balloon inflation. Since fluid is used to inflate the balloon, each sealing port, in contact with fluid, swells up against the guidewire and establishes a substantially fluid-tight seal with the guidewire. It is important to also note that due to the nature of hydrophilic material, each sealing port is highly lubricious when wet. Thus, wet hydrophilic material allows the guidewire to move easily through the sealing ports. Accordingly, the rapid-exchange catheter of the present invention can be removed from the patient""s body by withdrawing the rapid-exchange catheter over the guidewire while the guidewire remains in place in the patient.